Technical Field
The present invention relates to the automatic control field, in particular to a moving position control system for a moving apparatus.
Description of Related Art
Moving apparatus systems in the clean air environment of current wafer plants mainly employ two methods to position moving shafts.
One is a fully-closed-loop control using a barcode. A one-dimensional barcode and a servo driver are used to implement the fully-closed-loop control positioning, in which the control over the current loop, speed loop, motor position loop and absolute position loop is all done on the servo driver. Such controller for the servo driver imposes very high requirements for performance. All calculations are required to be done on the servo driver, thus affecting the speed and accuracy of the moving shaft motor. The advantage of this way is that any position on the barcode can be located.
The other is the semi-closed-loop positioning of the servo driver using a barcode label. According to this method, a servo driver and a servo motor are used to implement the semi-closed-loop control over positions, and after the conveying vehicle in the clean air environment is located at a positioning point on a track, a barcode scanner scans the one-dimensional barcode value to implement auxiliary positioning. This positioning manner has the following disadvantages: the moving apparatus cannot stop and locate at points with the one-dimensional barcode label; the moving apparatus cannot stop at places without the one-dimensional barcode label; once the moving apparatus has faults and stops at points with the label, the on-site scheduling system cannot know the position of the moving apparatus and let other moving apparatus to change routes, thus causing traffic jam to the sky track. Besides, if this positioning manner is employed, each of the positioning points of stations in the pre-designed layout must be pasted with a one-dimensional label to make a mark, and adding stations is very difficult and needs to add a one-dimensional barcode label at corresponding position of the sky track, causing trouble to the on-site construction in the clean air environment.